IMMUNOEXTRACTION OF PESTICIDES AT THE TRACE-LEVEL IN ENVIRONMENTAL MATRICES

The trace-level determination of a large variety of compounds requires high performance from analytical separation and detection as well as from sample preparation technique. The coupling of a preconcentration step using solid-phase extraction and liquid chromatography is now wid ely used in environmental analysis. However one factor limitating the sensitivity of the method is due to the lack of selective sorbents. Lo w detection limits cannot be obtained in complex environmental matrice s owing to many interfering compounds co-extracted and co-eluted with classical reversed-phase sorbents, i.e. octadecylsilicas and apolar co polymers. Immunoaffinity sorbents (ISs) have been synthetized for the extraction of several related compounds within different classes of pe sticides, such as phenylureas and triazines. These sorbents have been obtained by covalent bonding of polyclonal antibodies to a silica matr ix. The antibodies present a strong affinity for the antigen and a mor e or less strong one for other structurally-related analytes including their degradation products. The high degree of selectivity of these s orbents allows to reach the detection limits according to the regulato ry guidelines in the various studies matrices.